Field of the Invention
The present invention relates to a focusing state measuring apparatus, and more particularly, to a focusing state measuring apparatus which is capable of easily measuring a focusing state of a working apparatus with respect to a target object through a simpler structure.
Description of the Related Art
Generally, in addition to a laser processing apparatus such as a laser marking apparatus or a laser welding apparatus, an apparatus for performing various kinds of works (hereinafter, referred to as a working apparatus) includes an optical system for irradiating a laser beam onto a target object.
In order for the working apparatus to more stably and efficiently perform work on the target object, it is very important to accurately measure a focusing state of an optical system included in the working apparatus with respect to a target object and adjust the measured focusing state. In particular, in order to improve work quality of the target object on which work is performed, very important factors are a distance between the optical system included in the working apparatus and the target object (hereinafter, refereed to as a focusing distance) and an angle between the optical system included in the working apparatus (more specifically, a beam irradiated from the optical system) and a work plane of the target object (hereinafter, referred to as a focusing gradient).
For example, a laser marking apparatus, which is one of laser processing apparatuses, is an apparatus that receives a character, a figure, and the like from the outside and controls operations of a laser oscillator and a laser scanner to mark the received character, the received figure, and the like on a target object by using a laser beam. Since the laser beam irradiated by the laser scanner has a spot size of several to several tens of micrometers, it is very important to accurately and constantly maintain a focusing distance (that is, a focal length) and a focusing gradient.
As described above, there exist various methods for measuring and determining the focusing state of the working apparatus with respect to the target object. However, most apparatuses for measuring a focusing state utilizes various types of sensors so as to measure the focusing distance and the focusing gradient, or utilizes a CCD camera to capture an image of patterns or the like formed on the target object and then determine the focusing state through image processing with respect to the captured image. For example, a technology for determining a focusing state of an image by detecting a one-dimensional optical energy distribution from a two-dimensional optical energy distribution with respect to an image of a reference plane is disclosed in Korean Patent Application Publication No. 10-2005-0065249 (published on Jun. 29, 2005) entitled “FOCUS DETECTION AND METHOD AND APPARATUS FOR ADJUSTING GRADIENT BY USING THE SAME”.
However, the existing focusing state measuring apparatus has limitations in that a configuration thereof is complicated and costs thereof increase because the focusing state measuring apparatus need to be equipped with a capturing device such as a CCD camera or various types of sensors so as to determine a focusing state of a working apparatus with respect to a target object. In addition, the existing focusing state measuring apparatus has limitations in that a user cannot quickly and easily measure the focusing state of the working apparatus because it is necessary to perform processing on sensor values with respect to a focusing distance and a focusing gradient and perform image processing on an image.
Therefore, there is a need for a focusing state measuring apparatus which is capable of easily measuring a focusing state of a working apparatus with respect to a target object through a simpler structure.